Magnetic anisotropy and hyperfine interactions in CeFe₂, GdFe₂, and LuFe₂

Mössbauer-effect measurements on ⁵⁷Fe have been carried out on the cubic Laves compounds CeFe₂, GdFe₂, and LuFe₂ between 80 and 300 K. The analysis of the Mössbauer spectra allowed the determination of the easy axes of magnetization n→ in these compounds. In CeFe2, n→ is parallel to the [100] direction up to 150 K; it then becomes of type [uuw] with an angle of inclination with respect to the [100] axis of 20°. Just below the Curie temperature at 230 K, this angle increases to 30°. In GdFe2, n→ is parallel to the [100] direction at 80 and 300 K. In LuFe₂, n→ is of [uuw] type at 80 and 300 K. In terms of the phenomenological treatment of the magnetic anisotropy, the presence of an [uuw] type of easy axis of magnetization indicates that the bulk magnetic-anisotropy constant K₃ is of the same order of magnitude as K₁ and K₂. The hyperfine parameters of the three compounds are reported and discussed.